s-index/cve-2021-21349XStream SSRF CVE-2021-21349
Vulnerability
CVE-2021-21349: A Server-Side Forgery Request can be activated unmarshalling with XStream to access data streams from an arbitrary URL referencing a resource in an intranet or the local host.
Affected Versions
All versions until and including version 1.4.15 are affected, if using the version out of the box. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.
Description
The processed stream at unmarshalling time contains type information to recreate the formerly written objects. XStream creates therefore new instances based on these type information. An attacker can manipulate the processed input stream and replace or inject objects, that result in a server-side forgery request.
$ docker build -t cve-2021-21349 .
$ python -m http.server 8080
$ docker run -it --rm cve-2021-21349
Serving HTTP on :: port 8080 (http://[::]:8080/) ...
::ffff:127.0.0.1 - - [05/May/2021 16:35:39] "GET /internal.txt HTTP/1.1" 200 -
Change pom.xml to bellow
<dependency>
<groupId>com.thoughtworks.xstream</groupId>
<artifactId>xstream</artifactId>
<version>1.4.16</version>
</dependency>
Add NoTypePermission.NONE
import com.thoughtworks.xstream.security.NoTypePermission; // Add
XStream xstream = new XStream();
xstream.addPermission(NoTypePermission.NONE); // Add
xstream.fromXML(xml);